1. Field of the Invention
The present invention relates to a CMP pad conditioner used in a CMP device used for flattening a surface of a silicon wafer or the like.
2. Description of the Related Art
As a method of flattening a surface of a silicon wafer or the like, chemical mechanical polishing (abbreviated as “CMP,” hereinafter) has been used often in recent years.
FIG. 2 shows a configuration of a CMP device used conventionally.
In FIG. 2, a CMP device 51 includes a polishing head 54 and a conditioner 55 provided on a revolving table 53 that revolves about a revolving table shaft 52. A polishing pad 56 is formed on the upper surface of the revolving table 53.
The polishing head 54 includes a polishing head shaft 57 and a disk-shaped wafer carrier 58. A wafer 59 is suctioned onto a lower surface of the wafer carrier 58. The disk-shaped wafer carrier 58 revolves about the polishing head shaft 57.
The conditioner 55 includes a conditioner shaft 60 and a disk-shaped conditioning disk 61. The conditioning disk 61 revolves about the conditioner shaft 60.
A slurry supplying unit 62 supplies slurry 63 serving as abrasive material onto the polishing pad 56. The slurry 63 is incorporated into a contact surface between the wafer 59 and the polishing pad 56. The surface of the wafer 59 contacts with the polishing pad 56 on the revolving table 53 surface, and is ground with the slurry 63.
Abrasive grains composed of diamond or the like are fixed on an outer periphery lower surface of the conditioning disk 61. Then, the abrasive grains are rubbed against the polishing pad 56, and thereby grinds the polishing pad 56 surface. By virtue of this, the state is maintained that the surface of the polishing pad 56 is fluffed, so that the polishing condition can be constantly maintained.
Various improvements have been made for the CMP pad conditioner. An example of such techniques is described in Patent Documents 1, 2, and 3.
[Patent Document 1] Japanese Published Unexamined Patent Application No. 2003-305644
[Patent Document 2] Japanese Published Unexamined Patent Application No. 2005-161440
[Patent Document 3] Japanese Published Unexamined Patent Application No. 2001-113456
In a dresser for CMP processing described in Patent Document 1, plural lines of ridges are formed concentrically in an outer periphery part of a side face of a disk-shaped metal base. Then, the height of the ridge on an outer periphery side among the plural lines of ridges is formed lower than the height of the ridge of a middle part, while a layer of abrasive grains are fixed by soldering on the upper surfaces of these ridges. Further, in a pad conditioner described in Patent Document 2, super abrasive grains of two kinds having different grain sizes from each other are used. Then, super abrasive grains in a top part have the larger grain size, while those in a foot part have the smaller grain size.
In a CMP pad conditioner, the polishing pad is required to be grinded stably and flatly. Nevertheless, these two performance requirements conflict with each other, and hence these have been difficult to satisfy simultaneously.
Further, in a conditioner for CMP device described in Patent Document 3, a super abrasive grain surface having a blunt edge is provided on an inner periphery side of an end face that contacts with a polishing pad surface, while a super abrasive grain surface having a sharp edge is provided on an outer periphery side. In this conditioner for CMP device, the super abrasive grain surface having a blunt edge is provided on the inner periphery side, so that the flatness of the pad can be improved effectively. At the same time, the abrasive grain surface having a sharp edge is provided on the outer periphery side, so that the pad can be conditioned effectively.
Nevertheless, even when the abrasive grain surface having a sharp edge formed on the outer periphery side is provided, since the abrasive grains themselves do not have sharp edges, the abrasive grains located in the outermost periphery are solely effective in the grinding. This prevents stable grinding.